1. Field of the Invention
The present invention relates to pile drivers, particularly with regard to reciprocating pile drivers.
2. Description of the Related Art
Pile drivers are used to drive piles, such as beams, columns or supports, e.g., into the ground. Reciprocating pile drivers include a hammer that is placed onto the head, or top, of the pile by a hoist or a boom of, e.g., an excavator. The hammer typically includes a frame and a large ram, or weight, that is raised within the frame and then dropped onto the pile head. This process is repeated until the pile is driven into the ground to a desired depth. Commonly, a pneumatic or hydraulic cylinder is mounted to the frame to raise and then release the ram. However, in existing hammers, as the ram strikes the pile, significant forces are transmitted into the cylinder through a cylinder rod attached to the ram. As a result, these cylinders frequently break resulting in significant downtime and cost to replace the cylinder. Some existing hammers include a nylon or rubber mount at the connection between the ram and cylinder rod to dampen these forces, however, these mounts can deteriorate quickly.
As the pile is driven downwardly, the hammer frame is typically positioned on top of the pile or a drive cap positioned on top of the pile. If the frame does not rest on top of the pile or drive cap, the ram may strike the frame instead of the pile thereby transmitting the force of the falling ram into the frame. This force may be transferred from the frame into the boom of an excavator, e.g., causing damage to the excavator and possibly causing the excavator to tip over. Some previous hammers had to be lowered after each strike of the ram to keep the hammer frame in contact with the pile head. Other hammers were lowered within a large, elongate outer frame to keep the hammer frame in contact with the pile head. However, these outer frames required significant overhead room to position the hammer, thus, pile drivers utilizing these outer frames were mostly limited to outdoor applications.
What is needed is an improvement over the foregoing.